The Little Red School House
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Little Red School House clear sky chart from 2005-11-06 to 2024-03-23.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
34%
24871
17%
80901
10%
24767
42%
24767
21%
54838

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
19%
944
11%
4400
3%
926
30%
926
10%
3192
January11th to 20thNight
17%
950
10%
4396
4%
930
24%
930
8%
3486
January21st to endNight
18%
1038
7%
4769
3%
1023
25%
1023
8%
3763
February1st to 10thNight
20%
890
13%
2410
4%
890
26%
890
17%
1785
February11th to 20thNight
23%
740
20%
2219
8%
740
34%
740
19%
1514
February21st to endNight
18%
628
18%
1884
5%
628
30%
628
16%
1337
March1st to 10thNight
22%
760
13%
2280
7%
760
27%
760
16%
1624
March11th to 20thNight
27%
757
20%
2243
9%
757
38%
757
25%
1420
March21st to endNight
27%
600
15%
2000
11%
600
34%
600
16%
1413
April1st to 10thNight
27%
540
17%
1800
10%
540
38%
540
21%
1166
April11th to 20thNight
29%
533
20%
1775
13%
533
41%
533
21%
1173
April21st to endNight
30%
540
16%
1694
7%
540
39%
540
19%
1165
May1st to 10thNight
32%
540
15%
1620
9%
540
39%
540
24%
1096
May11th to 20thNight
41%
531
18%
1497
10%
531
47%
531
27%
999
May21st to endNight
46%
583
17%
1552
9%
582
51%
582
29%
1024
June1st to 10thNight
52%
540
18%
1440
10%
540
58%
540
37%
875
June11th to 20thNight
50%
540
21%
1440
13%
540
56%
540
37%
871
June21st to endNight
50%
540
18%
1440
10%
540
55%
540
31%
941
July1st to 10thNight
65%
525
16%
1400
12%
525
67%
525
41%
831
July11th to 20thNight
59%
522
22%
1392
15%
522
64%
522
42%
809
July21st to endNight
66%
591
23%
1487
16%
558
70%
558
45%
848
August1st to 10thNight
70%
537
22%
1486
20%
534
72%
534
40%
879
August11th to 20thNight
69%
534
23%
1751
22%
534
73%
534
39%
935
August21st to endNight
65%
594
25%
1980
25%
594
70%
594
37%
1062
September1st to 10thNight
57%
540
25%
1800
23%
540
64%
540
33%
1002
September11th to 20thNight
61%
646
34%
1906
27%
646
67%
646
39%
1067
September21st to endNight
50%
720
25%
1980
18%
720
56%
720
33%
1235
October1st to 10thNight
48%
720
25%
2006
18%
720
52%
720
32%
1235
October11th to 20thNight
31%
720
22%
2178
10%
720
44%
720
25%
1366
October21st to endNight
26%
792
17%
2574
10%
792
36%
792
19%
1729
November1st to 10thNight
28%
740
26%
2406
16%
740
42%
740
26%
1429
November11th to 20thNight
23%
760
19%
2470
9%
760
35%
760
18%
1641
November21st to endNight
22%
798
19%
2508
9%
798
34%
798
19%
1697
December1st to 10thNight
19%
950
13%
2660
4%
950
27%
950
18%
1928
December11th to 20thNight
21%
950
14%
3216
4%
948
29%
948
14%
2330
December21st to endNight
12%
1038
6%
4842
2%
1026
20%
1026
6%
3971

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
14%9%47%6%35%5%5%7%35%
78630
Night
15%10%47%5%3445%6%37%
81307
TransparencyDay
48%412%22%12%2
78331
Night
49%311%22%13%2
81127
SeeingDay
17%12%31%24%12%4
14831
Night
18%11%30%28%11%1
24895

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
14%13%8%10%6%45%5%45%27%
2527
11th to 20thDay
14%15%7%13%6%448%7%418%
2530
21st to endDay
19%25%7%8%5%23346%18%
2849
February1st to 10thDay
17%13%5%9%7%45%5%46%27%
1768
11th to 20thDay
15%11%5%7%7%44447%34%
1848
21st to endDay
16%13%5%8%6%34447%30%
1570
March1st to 10thDay
16%14%5%9%5%34445%30%
1900
11th to 20thDay
13%10%37%6%445%5%7%36%
1952
21st to endDay
20%11%5%8%7%46%5%46%25%
2400
April1st to 10thDay
16%11%48%5%45%45%6%31%
2160
11th to 20thDay
17%9%35%6%45%5%5%6%35%
2134
21st to endDay
20%8%36%6%3446%7%33%
2264
May1st to 10thDay
17%8%46%6%36%6%6%8%30%
2340
11th to 20thDay
18%8%37%6%3445%7%34%
2396
21st to endDay
13%6%46%6%45%5%6%8%37%
2725
June1st to 10thDay
9%5%35%5%35%6%6%8%45%
2520
11th to 20thDay
9%6%35%6%35%5%6%8%44%
2520
21st to endDay
10%6%36%6%46%7%7%9%36%
2520
July1st to 10thDay
7%5%35%5%35%5%7%9%45%
2520
11th to 20thDay
10%5%15%5%35%6%7%10%43%
2520
21st to endDay
6%425%6%46%7%8%10%42%
2743
August1st to 10thDay
7%426%6%45%7%6%10%42%
2441
11th to 20thDay
8%5%25%6%35%7%7%9%42%
2147
21st to endDay
8%4245%35%5%8%11%45%
2376
September1st to 10thDay
12%5%25%6%35%5%5%7%44%
2160
11th to 20thDay
11%5%2443445%8%49%
2034
21st to endDay
10%5%35%6%36%5%6%8%43%
1980
October1st to 10thDay
13%7%36%5%345%5%6%45%
1949
11th to 20thDay
19%8%36%6%35%446%35%
1781
21st to endDay
21%10%36%6%33446%35%
1782
November1st to 10thDay
12%8%45%5%33447%45%
1672
11th to 20thDay
16%9%47%6%3445%7%34%
1710
21st to endDay
18%10%48%5%34445%36%
1671
December1st to 10thDay
15%13%48%7%35%45%5%30%
1520
11th to 20thDay
13%13%5%10%6%445%5%6%28%
1918
21st to endDay
21%22%8%12%7%3433414%
2783
January1st to 10thNight
16%14%8%9%7%3433428%
4428
11th to 20thNight
16%18%8%11%7%346%6%418%
4440
21st to endNight
23%17%8%8%5%33435%21%
4816
February1st to 10thNight
16%13%5%7%7%34346%31%
2410
11th to 20thNight
14%11%47%6%34445%37%
2218
21st to endNight
19%11%47%5%34345%35%
1884
March1st to 10thNight
15%12%48%6%34445%34%
2280
11th to 20thNight
12%7%46%4345%5%7%43%
2243
21st to endNight
21%10%46%5%35%45%7%31%
2000
April1st to 10thNight
15%8%46%5%3445%8%37%
1800
11th to 20thNight
18%8%35%4445%46%38%
1775
21st to endNight
18%7%37%5%345%5%7%35%
1694
May1st to 10thNight
16%7%36%6%35%5%6%7%35%
1620
11th to 20thNight
16%6%35%5%345%5%7%40%
1496
21st to endNight
11%5%36%5%45%5%5%9%42%
1551
June1st to 10thNight
10%425%5%3446%7%49%
1440
11th to 20thNight
8%6%35%5%345%6%10%46%
1440
21st to endNight
11%5%35%446%5%5%9%42%
1440
July1st to 10thNight
6%425%5%35%5%6%9%51%
1440
11th to 20thNight
6%4244345%7%8%53%
1440
21st to endNight
4424435%6%7%10%51%
1575
August1st to 10thNight
45%246%36%5%7%8%50%
1495
11th to 20thNight
6%4135%345%5%10%53%
1751
21st to endNight
8%325%42445%8%55%
1980
September1st to 10thNight
10%5%36%43335%8%50%
1800
11th to 20thNight
9%424433447%55%
1906
21st to endNight
10%5%36%5%3447%7%46%
1980
October1st to 10thNight
12%5%25%434447%49%
2006
11th to 20thNight
17%7%34424337%43%
2178
21st to endNight
21%9%45%42345%7%36%
2574
November1st to 10thNight
12%8%35%5%2435%6%48%
2406
11th to 20thNight
14%10%48%6%3445%6%37%
2470
21st to endNight
17%9%46%6%34346%37%
2508
December1st to 10thNight
16%11%48%6%345%5%6%31%
2660
11th to 20thNight
15%14%5%9%5%34436%31%
3279
21st to endNight
24%18%7%9%6%34445%16%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
60%214%17%7%
2528
11th to 20thDay
66%210%13%8%
2530
21st to endDay
71%27%14%5%
2849
February1st to 10thDay
60%411%15%9%2
1768
11th to 20thDay
53%310%22%10%2
1858
21st to endDay
56%411%21%7%2
1570
March1st to 10thDay
57%49%21%7%1
1900
11th to 20thDay
49%312%24%11%1
1952
21st to endDay
61%412%17%5%1
2400
April1st to 10thDay
54%49%20%12%
2160
11th to 20thDay
49%410%21%12%4
2134
21st to endDay
51%5%12%18%12%2
2264
May1st to 10thDay
51%6%12%23%8%
2340
11th to 20thDay
50%5%11%21%12%1
2400
21st to endDay
45%5%12%20%16%2
2725
June1st to 10thDay
36%5%13%27%18%2
2520
11th to 20thDay
36%5%11%25%20%3
2520
21st to endDay
42%7%15%21%14%2
2520
July1st to 10thDay
35%5%13%27%16%3
2451
11th to 20thDay
35%6%13%27%16%2
2445
21st to endDay
35%6%16%26%15%3
2591
August1st to 10thDay
35%6%15%30%12%2
2426
11th to 20thDay
36%5%14%28%15%2
2147
21st to endDay
31%6%13%28%19%4
2376
September1st to 10thDay
38%5%12%24%18%4
2160
11th to 20thDay
32%5%11%30%18%3
2034
21st to endDay
38%5%10%27%19%1
1980
October1st to 10thDay
41%412%25%16%3
1949
11th to 20thDay
51%210%22%14%1
1781
21st to endDay
52%311%23%10%2
1782
November1st to 10thDay
39%315%24%17%2
1672
11th to 20thDay
50%412%22%12%1
1710
21st to endDay
53%310%23%10%
1671
December1st to 10thDay
56%313%20%7%1
1520
11th to 20thDay
57%311%20%7%1
1915
21st to endDay
78%37%9%3
2783
January1st to 10thNight
61%210%18%8%1
4428
11th to 20thNight
68%211%12%6%
4440
21st to endNight
68%29%15%6%
4816
February1st to 10thNight
56%310%18%11%2
2410
11th to 20thNight
50%310%22%14%1
2219
21st to endNight
54%39%20%11%3
1884
March1st to 10thNight
54%410%22%10%1
2280
11th to 20thNight
41%413%22%16%3
2243
21st to endNight
54%411%21%9%1
2000
April1st to 10thNight
46%312%25%13%2
1800
11th to 20thNight
47%37%22%16%4
1775
21st to endNight
49%49%21%14%2
1694
May1st to 10thNight
47%413%25%11%
1620
11th to 20thNight
43%5%11%24%15%1
1497
21st to endNight
40%6%14%20%17%3
1552
June1st to 10thNight
34%413%26%20%3
1440
11th to 20thNight
33%413%25%23%2
1440
21st to endNight
38%6%15%23%16%2
1440
July1st to 10thNight
30%5%16%29%15%5%
1400
11th to 20thNight
28%5%14%27%23%4
1392
21st to endNight
26%418%28%18%5%
1487
August1st to 10thNight
31%5%16%31%16%1
1486
11th to 20thNight
28%418%27%21%2
1751
21st to endNight
28%5%11%30%20%5%
1980
September1st to 10thNight
33%312%26%22%3
1800
11th to 20thNight
30%38%31%25%2
1906
21st to endNight
36%410%31%17%3
1980
October1st to 10thNight
35%5%9%28%20%2
2006
11th to 20thNight
42%29%25%19%2
2178
21st to endNight
50%310%24%12%1
2574
November1st to 10thNight
38%39%28%19%3
2406
11th to 20thNight
49%311%23%13%1
2470
21st to endNight
50%312%24%11%
2508
December1st to 10thNight
54%411%21%9%1
2660
11th to 20thNight
56%312%19%10%1
3281
21st to endNight
73%28%12%4
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
22%17%36%20%4
270
11th to 20thDay
26%21%33%16%31
270
21st to endDay
25%18%34%19%21
297
February1st to 10thDay
24%20%40%14%2
270
11th to 20thDay
26%22%33%17%3
270
21st to endDay
25%19%41%12%2
225
March1st to 10thDay
21%27%39%11%2
270
11th to 20thDay
25%20%34%16%5%
303
21st to endDay
30%18%27%17%6%1
470
April1st to 10thDay
24%16%32%20%8%
420
11th to 20thDay
23%20%25%20%10%1
412
21st to endDay
25%16%33%17%8%1
420
May1st to 10thDay
24%16%29%21%8%3
423
11th to 20thDay
21%12%33%20%11%3
542
21st to endDay
15%10%34%24%12%6%
679
June1st to 10thDay
10%10%33%28%13%5%
630
11th to 20thDay
13%8%32%27%17%3
630
21st to endDay
12%11%34%28%11%5%
630
July1st to 10thDay
9%424%33%18%12%
621
11th to 20thDay
12%6%28%31%16%7%
618
21st to endDay
8%7%27%34%18%5%
684
August1st to 10thDay
7%425%34%21%10%
560
11th to 20thDay
10%419%31%26%10%
439
21st to endDay
8%421%37%21%8%
495
September1st to 10thDay
15%6%23%31%20%5%
450
11th to 20thDay
11%420%32%24%9%
450
21st to endDay
12%11%25%29%18%6%
450
October1st to 10thDay
18%7%29%26%15%5%
419
11th to 20thDay
22%23%33%17%41
270
21st to endDay
33%14%35%15%3
297
November1st to 10thDay
14%17%37%23%6%3
270
11th to 20thDay
24%19%35%16%6%1
270
21st to endDay
26%11%40%19%3
270
December1st to 10thDay
21%24%34%16%4
270
11th to 20thDay
21%17%41%17%3
270
21st to endDay
27%22%37%12%2
297
January1st to 10thNight
21%17%35%22%4
950
11th to 20thNight
23%18%34%20%41
950
21st to endNight
22%14%34%26%4
1045
February1st to 10thNight
23%13%37%22%4
890
11th to 20thNight
21%16%34%25%3
743
21st to endNight
23%19%36%19%3
628
March1st to 10thNight
23%14%36%21%6%
760
11th to 20thNight
16%13%39%25%6%1
757
21st to endNight
26%12%29%25%8%1
600
April1st to 10thNight
20%12%35%25%7%
540
11th to 20thNight
23%13%32%23%8%1
533
21st to endNight
23%9%32%27%9%
540
May1st to 10thNight
19%8%36%29%8%
540
11th to 20thNight
19%429%33%14%1
531
21st to endNight
14%5%27%34%20%1
584
June1st to 10thNight
11%425%45%14%1
540
11th to 20thNight
10%6%27%42%14%1
540
21st to endNight
12%425%40%18%1
540
July1st to 10thNight
8%217%40%29%4
525
11th to 20thNight
7%422%41%24%3
522
21st to endNight
5%220%47%24%2
591
August1st to 10thNight
6%213%48%27%4
537
11th to 20thNight
7%313%40%32%5%
534
21st to endNight
9%217%38%31%3
594
September1st to 10thNight
12%419%34%27%4
540
11th to 20thNight
9%5%19%35%27%4
646
21st to endNight
12%7%23%34%22%3
720
October1st to 10thNight
14%6%26%33%18%2
720
11th to 20thNight
21%14%31%26%8%
720
21st to endNight
26%13%29%24%7%
792
November1st to 10thNight
16%14%38%20%10%2
740
11th to 20thNight
19%18%34%23%5%1
760
21st to endNight
22%12%38%21%6%
798
December1st to 10thNight
21%16%37%22%4
950
11th to 20thNight
23%14%35%24%4
950
21st to endNight
31%16%32%19%2
1045
Page generated at 2024-03-19 22:31:06. Version ac07

Copyright © 2024 Attilla Danko.


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